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On Energy Farms, Technology Milks the Wind

THE windmill is a centuries-old technology originally developed to pump water and grind grain, but it could play an important role in solving two serious problems facing the United States: generating an adequate supply of electricity and reducing the emission of greenhouse gases.

Wind turbines have been used for generating electricity for more than a century, beginning with experiments by a Danish meteorologist, Poul la Cour, in the 1890's and his founding of the Society of Wind Electricians in 1905.

Despite refinements in the 20th century, development did not begin in earnest until the oil crisis in the 1970's made the electricity supply expensive and less reliable. The 1970's and 1980's saw a proliferation of turbine designs, ranging from two- and three-propeller horizontal generator designs to a vertical model that resembled an eggbeater. But this country's nascent wind generation industry got a bad rap in the 1980's when investments in wind generators failed because of cheap electricity from fossil and nuclear fuels and the inefficient design of some turbines.

Wind turbines have now become much more efficient, thanks in large part to the Danish windmill industry. Now dozens of manufacturers are cranking out turbine models, from small designs, each aimed at providing power for a single house, to huge machines with 100-foot blades that can supply between two and three million kilowatt-hours in a year, enough to power at least 500 households. California, which has the most developed wind-power industry of any state, has more than 15,000 turbines creating enough energy for about a million people. And in the late 1990's, Enron Wind, a wind-turbine developer based in California, installed the three largest wind-generation plants in the world in the American Midwest: two plants, each producing more than a hundred megawatts, in Lake Benton, Minn., and a 193-megawatt plant in Storm Lake, Iowa.

The impetus for generating clean power is being spurred by efforts to reduce greenhouse gases. Currently, two-thirds of the electricity in the United States is generated by burning fossil fuels like coal, gas and oil. Such combustion pumped 2,245 million metric tons of carbon dioxide into the atmosphere in 1999, according to the Department of Energy and the Environmental Protection Agency. That was an increase of 1.35 percent over the previous year.

The more power produced by wind, the less need be produced by burning fossil fuels. But wind turbines remain a relatively untapped resource. Wind currently contributes three billion kilowatt-hours annually, less than 1 percent of the national supply.

Wind power has a few benefits over more common ways to generate electricity. Wind ''farms,'' with dozens or even hundreds of turbines, can be built cheaply and quickly, and they can be easily expanded. Their operational costs are not subject to fuel prices, and the cost per kilowatt-hour is comparable to the cost for plants burning fossil fuels.

A disadvantage of wind power is its unreliability. Although wind farms are situated to take advantage of strong prevailing winds, variations in wind speed cause unpredictable fluctuations in the capacity of a wind turbine. Even the most efficient design fails to capture 40 percent of the energy in the wind. But since it's ''free'' energy, failing to tap it all is not such a big problem.

Despite the advantages of wind generation, it has a large number of earnest opponents. Some people just do not want to have wind turbines nearby. The turbines are huge structures that are visible from great distances because they need unobstructed access to air currents. So many zoning boards and prospective residents say they are eyesores that contribute to visual blight.

The large structures also require deep concrete foundations, and that heavy construction has its own impact on rural settings. Such excavation leads to local air pollution and the risk of erosion at the sites and their access roads. And wind farms gobble up territory, taking up considerably more land than other electrical generators to generate a comparable amount of electricity.

Many older models drew opposition because they were noisy, but newer designs are quieter. The wind generation industry says modern turbines are no louder than refrigerators when heard from the distance that most turbines are placed from populated areas.

There is also controversy over the impact of wind turbines on the environment, especially bird life, because raptors like golden eagles are drawn to prey sheltering near the turbines and can be killed by the spinning blades. The Sierra Club, the United States Fish and Wildlife Service, and the Audubon Society all recognize bird mortality as a significant problem with wind generators.

The Department of Energy's goal is to increase the contribution of wind power to electricity generation nationwide to 5 percent by 2020, and that may be within reach. The department has plans on file from several power companies that want to build large-scale wind farms between now and 2019 in Texas, New Jersey, Massachusetts and Minnesota, with smaller plants in Pennsylvania, Connecticut and upstate New York, near Watertown.